Systems, devices, and methods for eyeboxes with heterogeneous exit pupils

ABSTRACT

Systems, devices, and methods for engineering the eyebox of a display using multiple heterogeneous exit pupils are described. The eyebox of a display includes at least two heterogeneous exit pupils that are different from one another in terms of size and/or shape. Heterogeneous exit pupils may overlap, one may encompass another, or they may be completely spatially-separated from one another. Such configurations enable specific eyebox and/or visual display configurations that can be advantageous in certain applications. An example in which a scanning laser-based wearable heads-up virtual retina display implements a holographic combiner that is engineered to provide multiple heterogeneous exit pupils is described.

TECHNICAL FIELD

The present systems, devices, and methods generally relate to opticaldevices and particularly relate to engineering the eyebox of a wearableheads-up display.

BACKGROUND Description of the Related Art Holographic Optical Elements

For the purposes of the present systems, devices, and methods, aholographic optical element is an optical element that includes at leastone hologram. Generally, a holographic optical element comprises one ormore layer(s) of holographic material with at least one hologramrecorded, embedded, stored, or included therein or thereon(collectively, “in”). A holographic optical element may be a film and/orlaminate structure comprising any number of layers and any number ofholograms per layer, depending on the specific application.

Wearable Heads-Up Displays

A head-mounted display is an electronic device that is worn on a user'shead and, when so worn, secures at least one electronic display within aviewable field of at least one of the user's eyes, regardless of theposition or orientation of the user's head. A wearable heads-up displayis a head-mounted display that enables the user to see displayed contentbut also does not prevent the user from being able to see their externalenvironment. The “display” component of a wearable heads-up display iseither transparent or at a periphery of the user's field of view so thatit does not completely block the user from being able to see theirexternal environment. Examples of wearable heads-up displays include:the Google Glass®, the Optinvent Ora®, the Epson Moverio®, and the SonyGlasstron®, just to name a few.

The optical performance of a wearable heads-up display is an importantfactor in its design. When it comes to face-worn devices, however, usersalso care a lot about aesthetics. This is clearly highlighted by theimmensity of the eyeglass (including sunglass) frame industry.Independent of their performance limitations, many of the aforementionedexamples of wearable heads-up displays have struggled to find tractionin consumer markets because, at least in part, they lack fashion appeal.Most wearable heads-up displays presented to date employ large displaycomponents and, as a result, most wearable heads-up displays presentedto date are considerably bulkier and less stylish than conventionaleyeglass frames.

A challenge in the design of wearable heads-up displays is to minimizethe bulk of the face-worn apparatus will still providing displayedcontent with sufficient visual quality. There is a need in the art forwearable heads-up displays of more aesthetically-appealing design thatare capable of providing high-quality images to the user withoutlimiting the user's ability to see their external environment.

Eyebox

In near-eye optical devices such as rifle scopes and wearable heads-updisplays, the range of eye positions (relative to the device itself)over which specific content/imagery provided by the device is visible tothe user is generally referred to as the “eyebox.” An application inwhich content/imagery is only visible from a single or small range ofeye positions has a “small eyebox” and an application in whichcontent/imagery is visible from a wider range of eye positions has a“large eyebox.” The eyebox may be thought of as a volume in spacepositioned near the optical device. When the eye of the user (and moreparticularly, the pupil of the eye of the user) is positioned insidethis volume and facing the device, the user is able to see all of thecontent/imagery provided by the device. When the eye of the user ispositioned outside of this volume, the user is not able to see at leastsome of the content/imagery provided by the device.

The geometry (i.e., size and shape) of the eyebox is an importantproperty that can greatly affect the user experience for a wearableheads-up display. For example, if the wearable heads-up display has asmall eyebox that centers on the user's pupil when the user is gazingdirectly ahead, some or all content displayed by the wearable heads-updisplay may disappear for the user when the user gazes even slightlyoff-center, such as slightly to the left, slightly to the right,slightly up, or slightly down. Furthermore, if a wearable heads-updisplay that has a small eyebox is designed to align that eyebox on thepupil for some users, the eyebox will inevitably be misaligned relativeto the pupil of other users because not all users have the same facialstructure. Unless a wearable heads-up display is deliberately designedto provide a glanceable display (i.e., a display that is not alwaysvisible but rather is only visible when the user gazes in a certaindirection), it is generally advantageous for a wearable heads-up displayto have a large eyebox.

Demonstrated techniques for providing a wearable heads-up display with alarge eyebox generally necessitate adding more bulky optical componentsto the display. Technologies that enable a wearable heads-up display ofminimal bulk (relative to conventional eyeglass frames) to provide alarge eyebox are generally lacking in the art.

BRIEF SUMMARY

A holographic optical element (“HOE”) may be summarized as including: atleast one layer of holographic material, wherein the at least one layerof holographic material includes: a first hologram to receive light froma light source and direct the light to a first exit pupil at orproximate an eye of a user, the first exit pupil having a first area;and a second hologram to receive light from the light source and directthe light to a second exit pupil at or proximate the eye of the user,the second exit pupil having a second area that is different from thefirst area.

The first hologram and the second hologram may be positioned andoriented with respect to one another to cause the first exit pupil andthe second exit pupil to at least partially overlap with one another atthe eye of the user. The first hologram and the second hologram may bepositioned and oriented with respect to one another to cause the secondexit pupil to encompass the first exit pupil at the eye of the user.

The first hologram and the second hologram may be positioned andoriented with respect to one another to cause the first exit pupil andthe second exit pupil to be completely spatially-separated from oneanother at the eye of the user. The at least one layer of holographicmaterial may further include at least one additional hologram, eachadditional hologram to receive light from the light source and directthe light to a respective exit pupil at or proximate the eye of theuser, and each respective exit pupil may have a respective area that isdifferent from the area of at least one of the other exit pupils.

The at least one layer of holographic material may include a holographicmaterial selected from a group consisting of: a holographic film, asilver halide compound, and a photopolymer. The at least one layer ofholographic material may include a first layer of holographic materialand both the first hologram and the second hologram may be in the firstlayer of holographic material. Alternatively, the at least one layer ofholographic material may include a first layer of holographic materialand a second layer of holographic material, the second layer ofholographic material carried by the first layer of holographic material,and the first hologram may be in the first layer of holographic materialand the second holograms may be in the second layer of holographicmaterial.

The first exit pupil may have a first geometry and the second exit pupilmay have a second geometry that is different from the first geometry.The first hologram and the second hologram may both be multiplexedholograms that implement a same form of multiplexing, the form ofmultiplexing implemented by both the first hologram and the secondhologram selected from a group consisting of: angle multiplexing,wavelength multiplexing, angle and wavelength multiplexing, and spatialmultiplexing holograms. The first hologram may converge the light to thefirst exit pupil with a first rate of convergence and the secondhologram may converge the light to the second exit pupil with the samefirst rate of convergence.

A wearable heads-up display (“WHUD”) may be summarized as including: asupport structure that in use is worn on a head of a user; a scanninglaser projector carried by the support structure; and a holographiccombiner carried by the support structure, wherein the holographiccombiner is positioned within a field of view of an eye of the user whenthe support structure is worn on the head of the user, and wherein theholographic combiner comprises at least one layer of holographicmaterial and the at least one layer of holographic material includes: afirst hologram to receive light from the scanning laser projector anddirect the light to a first exit pupil at or proximate the eye of theuser, the first exit pupil having a first area; and a second hologram toreceive light from the scanning laser projector and direct the light toa second exit pupil at or proximate the eye of the user, the second exitpupil having a second area that is different from the first area. Thesupport structure may have a general shape and appearance of aneyeglasses frame and the holographic combiner may further include aneyeglass lens that carries the at least one layer of holographicmaterial. The first hologram and the second hologram may be positionedand oriented with respect to one another to cause the first exit pupiland the second exit pupil to at least partially overlap with one anotherat the eye of the user. The first hologram and the second hologram maybe positioned and oriented with respect to one another to cause thesecond exit pupil to encompass the first exit pupil at the eye of theuser. The first hologram and the second hologram may be positioned andoriented with respect to one another to cause the first exit pupil andthe second exit pupil to be completely spatially-separated from oneanother at the eye of the user.

The at least one layer of holographic material in the holographiccombiner may further include at least one additional hologram, eachadditional hologram to receive light from the scanning laser projectorand direct the light to a respective exit pupil at or proximate the eyeof the user, and each respective exit pupil may have a respective areathat is different from the area of at least one of the other exitpupils. The first exit pupil may have a first geometry and the secondexit pupil may have a second geometry that is different from the firstgeometry. The first hologram and the second hologram of the holographiccombiner may both be multiplexed holograms that implement a same form ofmultiplexing, the form of multiplexing implemented by both the firsthologram and the second hologram selected from a group consisting of:angle multiplexing, wavelength multiplexing, angle and wavelengthmultiplexing, and spatial multiplexing. The first hologram may convergethe light from the scanning laser projector to the first exit pupil witha first rate of convergence and the second hologram may converge thelight from the scanning laser projector to the second exit pupil witheither a different rate of convergence of with the same first rate ofconvergence

A method of operating a WHUD, the WHUD including a scanning laserprojector and a holographic combiner positioned within a field of viewof an eye of a user when the WHUD is worn on a head of the user, may besummarized as including: directing a first light signal towards theholographic combiner by the scanning laser projector; redirecting thefirst light signal towards a first exit pupil that has a first area ator proximate the eye of the user by a first hologram of the holographiccombiner; directing a second light signal towards the holographiccombiner by the scanning laser projector; and redirecting the secondlight signal towards a second exit pupil that has a second area at orproximate the eye of the user by a second hologram of the holographiccombiner, the second area different from the first area. Redirecting thefirst light signal towards a first exit pupil that has a first area ator proximate the eye of the user by a first hologram of the holographiccombiner may include converging the first light signal towards the firstexit pupil that has the first area at or proximate the eye of the userby the first hologram of the holographic combiner. Redirecting thesecond light signal towards a second exit pupil that has a second areaat or proximate the eye of the user by a second hologram of theholographic combiner may include converging the second light signaltowards the second exit pupil that has the second area at or proximatethe eye of the user by the second hologram of the holographic combiner.Converging the first light signal towards the first exit pupil that hasthe first area at or proximate the eye of the user by the first hologramof the holographic combiner may include converging the first lightsignal towards the first exit pupil with a first rate of convergence bythe first hologram of the holographic combiner, and converging thesecond light signal towards the second exit pupil may include convergingthe second light signal towards the second exit pupil with either adifferent rate of convergence or with the same first rate of convergenceby the second hologram of the holographic combiner.

Redirecting the second light signal towards a second exit pupil that hasa second area at or proximate the eye of the user by a second hologramof the holographic combiner may include redirecting the second lightsignal towards a second exit pupil that at least partially overlaps withthe first exit pupil at or proximate the eye of the user by the secondhologram of the holographic combiner. Redirecting the second lightsignal towards a second exit pupil that at least partially overlaps withthe first exit pupil at or proximate the eye of the user by the secondhologram of the holographic combiner may include redirecting the secondlight signal towards a second exit pupil that encompasses the first exitpupil at or proximate the eye of the user by the second hologram of theholographic combiner. The method may further include: directing at leastone additional light signal towards the holographic combiner by thescanning laser projector; and redirecting each additional light signaltowards a respective exit pupil at or proximate the eye of the user by arespective hologram of the holographic combiner, each respective exitpupil having a respective area that is different from the area of atleast one of the other exit pupils.

A WHUD may be summarized as including: a support structure that in useis worn on a head of a user; a display module carried by the supportstructure and operative to provide a visual display to the user, whereinthe visual display has an eyebox that comprises: a first exit pupil ator proximate an eye of the user, the first exit pupil having a firstarea; and at least second exit pupil at or proximate the eye of theuser, the second exit pupil having a second area that is different fromthe first area. The first exit pupil and the second exit pupil may atleast partially overlap with one another in the eyebox of the WHUD. Thesecond exit pupil may encompass the first exit pupil in the eyebox ofthe WHUD. The first exit pupil and the second exit pupil may becompletely spatially-separated from one another and not overlap at allin the eyebox of the WHUD. The eyebox of the visual display may furtherinclude at least one additional exit pupil, wherein each respective exitpupil may have a respective area that is different from the area of atleast one of the other exit pupils.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

In the drawings, identical reference numbers identify similar elementsor acts. The sizes and relative positions of elements in the drawingsare not necessarily drawn to scale. For example, the shapes of variouselements and angles are not necessarily drawn to scale, and some ofthese elements are arbitrarily enlarged and positioned to improvedrawing legibility. Further, the particular shapes of the elements asdrawn are not necessarily intended to convey any information regardingthe actual shape of the particular elements, and have been solelyselected for ease of recognition in the drawings.

FIG. 1 is a partial-cutaway perspective view of a wearable heads-updisplay that implements multiple heterogeneous exit pupils in accordancewith the present systems, devices, and methods.

FIG. 2 is an illustrative diagram of a wearable heads-up displayincluding a holographic combiner that provides multiple heterogeneousexit pupils at the eye of the user in accordance with the presentsystems, devices, and methods.

FIG. 3 is an illustrative diagram showing a simplified operation of aholographic optical element that provides multiple heterogeneous exitpupils in accordance with the present systems, devices, and methods.

FIG. 4 is an illustrative diagram of a wearable heads-up displayincluding a holographic combiner that provides multiple heterogeneousexit pupils at the eye of the user in accordance with the presentsystems, devices, and methods.

FIG. 5 is a flow-diagram showing a method of operating a wearableheads-up display in accordance with the present systems, devices, andmethods.

DETAILED DESCRIPTION

In the following description, certain specific details are set forth inorder to provide a thorough understanding of various disclosedembodiments. However, one skilled in the relevant art will recognizethat embodiments may be practiced without one or more of these specificdetails, or with other methods, components, materials, etc. In otherinstances, well-known structures associated with portable electronicdevices and head-worn devices, have not been shown or described indetail to avoid unnecessarily obscuring descriptions of the embodiments.

Unless the context requires otherwise, throughout the specification andclaims which follow, the word “comprise” and variations thereof, suchas, “comprises” and “comprising” are to be construed in an open,inclusive sense, that is as “including, but not limited to.”

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structures, orcharacteristics may be combined in any suitable manner in one or moreembodiments.

As used in this specification and the appended claims, the singularforms “a,” “an,” and “the” include plural referents unless the contentclearly dictates otherwise. It should also be noted that the term “or”is generally employed in its broadest sense, that is as meaning “and/or”unless the content clearly dictates otherwise.

The headings and Abstract of the Disclosure provided herein are forconvenience only and do not interpret the scope or meaning of theembodiments.

The various embodiments described herein provide systems, devices, andmethods for engineering the eyebox and/or display interface of awearable heads-up display (WHUD″). The eyebox and/or display interfaceof a WHUD is engineered by spatially and geometrically arrangingmultiple heterogeneous exit pupils at or proximate the eye of the user,where at least two of the exit pupils have different respective sizes(e.g., areas) and/or geometries. While the principles described hereinare generally applicable to any form of optical device that employs aneyebox, they are particularly well-suited for use in near-eye displaysystems such as WHUDs. A specific example of an application ofheterogeneous exit pupils in a scanning laser-based WHUD architecture isdescribed.

Generally, a scanning laser-based WHUD is a form of virtual retinadisplay in which a scanning laser projector (“SLP”) draws a raster scanonto the eye of the user. In the absence of any further measure the SLPprojects light over a fixed area called the exit pupil of the display.In order for the user to see displayed content the exit pupil typicallyneeds to align with, be encompassed by, or overlap with the entrancepupil of the user's eye. The full resolution and/or field of view of thedisplay is visible to the user when the exit pupil of the display iscompletely contained within the entrance pupil of the eye. For thisreason, a scanning laser-based WHUD typically employs a relatively smallexit pupil that is equal to or smaller than the expected size of theentrance pupil of the user's eye (e.g., less than or equal to about 4 mmin diameter).

The eyebox of a scanning laser-based WHUD is defined by the geometry ofthe exit pupil of the display at or proximate the eye of the user. Ascanning laser-based WHUD that employs a small exit pupil in order toachieve maximum display resolution and/or field of view typically hasthe drawback of having a relatively small eyebox. For example, the exitpupil may be aligned with the center of the user's eye so that the eye'spupil is located “within the eyebox” when the user is gazing directlyahead but the eye's pupil may quickly leave the eyebox if and when theuser glances anywhere off-center. A larger eyebox may be achieved byincreasing the size of the exit pupil but this typically comes at thecost of reducing the display resolution and/or field of view.

Various examples of scanning laser-based WHUDs are described in, atleast, U.S. Non-Provisional patent application Ser. No. 15/046,234, U.S.Non-Provisional patent application Ser. No. 15/046,254, and U.S.Non-Provisional patent application Ser. No. 15/046,269, each of whichincludes a holographic combiner positioned in the field of view of atleast one of the user to receive light from the SLP and redirect (e.g.,converge) the light towards the eye of the user. In accordance with thepresent systems, devices, and methods, such a holographic combiner maybe engineered to provide multiple heterogeneous exit pupils at orproximate the eye of the user that, in combination, may form virtuallyany desired eyebox and/or display interface structure.

Some WHUD architectures, such as those referenced above, employ multipleexit pupils for the purpose of eyebox expansion by exit pupilreplication. In such architectures, each respective exit pupil maytypically correspond to an optically replicated or repeated instance ofthe same exit pupil. That is, each replicated or repeated instance ofthe exit pupil may have substantially the same size and geometry as theother instances of the exit pupil, meaning all exit pupils aresubstantially homogeneous. Spatially distributing multiple homogeneousinstances of the same exit pupil over a relatively larger area of theuser's eye may produce an expanded eyebox compared to the area of thesingle exit pupil on its own, and in such applications it is generallydesirable for all instances of the exit pupil to have substantially thesame size and shape. Conversely, in the present systems, devices, andmethods, eyeboxes are engineered by a combination of heterogeneous exitpupils, at least two of which embody different sizes, shapes, and/orgeometries. In this way, eyeboxes and/or display interfaces that areadvantageous for certain applications may be provided.

FIG. 1 is a partial-cutaway perspective view of a WHUD 100 thatimplements multiple heterogeneous exit pupils in accordance with thepresent systems, devices, and methods. WHUD 100 includes a supportstructure 110 that in use is worn on the head of a user and has ageneral shape and appearance of an eyeglasses (e.g., sunglasses) frame.Support structure 110 carries multiple components, including: a SLP 120,a holographic combiner 130 that provides multiple heterogeneous exitpupils, and an optic 140 for routing light signals from SLP 120 toholographic combiner 130. Portions of SLP 120 and optic 140 may becontained within an inner volume of support structure 110; however, FIG.1 provides a partial-cutaway view in which regions of support structure110 have been removed in order to render visible portions of SLP 120 andoptic 140 that may otherwise be concealed.

Throughout this specification and the appended claims, the term“carries” and variants such as “carried by” are generally used to referto a physical coupling between two objects. The physical coupling may bedirect physical coupling (i.e., with direct physical contact between thetwo objects) or indirect physical coupling that may be mediated by oneor more additional objects. Thus, the term carries and variants such as“carried by” are meant to generally encompass all manner of direct andindirect physical coupling, including without limitation: carried on,carried within, physically coupled to, and/or supported by, with orwithout any number of intermediary physical objects therebetween.

SLP 120 may include multiple laser diodes (e.g., a red laser diode, agreen laser diode, and/or a blue laser diode) and at least one scanmirror (e.g., a single two-dimensional scan mirror or twoone-dimensional scan mirrors, which may be, e.g., MEMS-based orpiezo-based). SLP 120 may be communicatively coupled to (and supportstructure 110 may further carry) a processor and a non-transitoryprocessor-readable storage medium or memory storing processor-executabledata and/or instructions that, when executed by the processor, cause theprocessor to control the operation of SLP 120. For ease of illustration,FIG. 1 does not call out a processor or a memory. In someimplementations, SLP 120 may employ the systems, devices, and methodsfor focusing laser projectors described in U.S. Provisional PatentApplication Ser. No. 62/322,128.

Optic 140 may perform a variety of different roles or may not beincluded at all depending on the specific implementation. For example,in some applications optic 140 may be a form of eyebox expansion opticsuch as any of those described in U.S. Non-Provisional patentapplication Ser. No. 15/046,234, U.S. Non-Provisional patent applicationSer. No. 15/046,254, and U.S. Non-Provisional patent application Ser.No. 15/046,269. In the illustrated implementation of WHUD 100, SLP 120is oriented to initially project light towards the ear of the user andoptic 140 is used to re-route the projected light back towardsholographic combiner 130. This configuration is used in WHUD 100 toinfluence/accommodate the form factor of support structure 110 and toprovide a desired path length for the optical path of laser lightprojected from SLP 120 to holographic combiner 130, but alternative WHUDimplementations may have different requirements and may or may notinclude an optic such as optic 140.

Holographic combiner 130 is a HOE that is positioned within a field ofview of at least one eye of the user when support structure 110 is wornon the head of the user. Holographic combiner 130 is sufficientlyoptically transparent to wavelengths other than the wavelengths of laserlight provided by SLP 120 in order to permit light from the user'senvironment (i.e., “environmental light”) to pass through to the user'seye. In the illustrated example of FIG. 1, support structure 110 carriesa transparent eyeglass lens 150 (e.g., a prescription eyeglass lens,non-prescription eyeglass lens) and holographic combiner 130 comprisesat least one layer of holographic material that is adhered to, affixedto, laminated with, carried in or upon, or otherwise integrated witheyeglass lens 150. The at least one layer of holographic material mayinclude a holographic film, a photopolymer such as Bayfol®HX availablefrom Bayer MaterialScience AG, and/or a silver halide compound and may,for example, be integrated with transparent lens 150 using any of thetechniques described in U.S. Provisional Patent Application Ser. No.62/214,600. As will be described in more detail later, the at least onelayer of holographic material in holographic combiner 130 includes i) afirst hologram to receive light from SLP 120 and direct (e.g., reflectand converge, collimate, or diverge) the light to a first exit pupilhaving a first area at or proximate the eye of a user, and ii) a secondhologram to receive light from SLP 120 and direct (e.g., reflect andconverge, collimate, or diverge) the light to a second exit pupil havinga second area at or proximate the eye of the user. Advantageously, thesecond area of the second exit pupil is different from (e.g., larger orsmaller than) the first area of the first exit pupil and/or the firsexit pupil has a first geometry (e.g., a first shape) and the secondexit pupil has a second geometry (e.g., a second shape) that isdifferent form the first geometry of the first exit pupil. The relativesizes and geometries of the first exit pupil and the second exit pupilmay be selected to provide any desired eyebox geometry and/or displayinterface layout.

The term “area” is used herein to refer to both the magnitude (e.g., 10mm²) and the shape/geometry (e.g., circular, elliptical, rectangular,irregular) of an exit pupil. In most conventional optical systems, anexit pupil has a generally round geometry, such as a substantiallycircular or elliptical geometry. In an exemplary implementation of thepresent systems, devices, and methods, multiple heterogeneous exitpupils may each adopt a similar circular geometry having a differentsize, but in other implementations a first exit pupil may adopt such acircular geometry and a second exit pupil may adopt a substantiallydifferent geometry, such as an elliptical or oval geometry, or anirregular amorphous geometry. In the first example, a first exit pupiland a second exit pupil may both be circular in shape but the magnitudeof the first area of the first exit pupil may be different from themagnitude of the second area of the second exit pupil. In the secondexample, the first area of the first exit pupil and the second area ofthe second exit pupil may have the same magnitude but the respectiveshapes of the two exit pupils may be different. In both cases, the firstarea of the first exit pupil and the second area of the second exitpupil are considered herein to be “different” from one another.

Depending on the specific implementation, the first exit pupil and thesecond exit pupil may at least partially overlap with one another (e.g.,the first exit pupil may at least partially overlap the second exitpupil and/or the second exit pupil may at least partially overlap thefirst exit pupil). As will be discussed in more detail later on, in someapplications it may be advantageous for one exit pupil (e.g., the secondexit pupil) to completely encompass another exit pupil (e.g., the firstexit pupil); however, in still other applications the first exit pupiland the second exit pupil may be completely spatially-separated from oneanother at the eye of the user (i.e., may not overlap at all at the eyeof the user). In accordance with the present systems, devices, andmethods, the number, geometries, sizes and arrangement of heterogeneousexit pupils may advantageously be selected (e.g., engineered) to suitthe eyebox and/or display interface requirements of any particularapplication.

FIG. 2 is an illustrative diagram of a WHUD 200 including a holographiccombiner 230 that provides multiple heterogeneous exit pupils 281 and282 at the eye 290 of the user in accordance with the present systems,devices, and methods. WHUD 200 may be substantially similar to WHUD 100from FIG. 1, although in FIG. 2 no support structure (e.g., supportstructure 110) is illustrated in order to reduce clutter. As with WHUD100, WHUD 200 comprises a SLP 220 (which includes a RGB laser module 221and at least one MEMS-based scan mirror 222) and holographic combiner230 is carried by an eyeglass lens 250. As previously described, thecombination of holographic combiner 230 and eyeglass lens 250 issufficiently transparent (to wavelengths of light other than thoseprovided by SLP 220) to allow environmental light 295 to pass through toeye 290.

Holographic combiner 230 includes an HOE comprising at least one layerof holographic material. The at least one layer of holographic materialincludes a first hologram and at least a second hologram. The firsthologram receives a first set of light signals 271 (represented by lineswith large dashes) from SLP 220 and directs (e.g., redirects and/orconverges) first set of light signals 271 to a first exit pupil 281 ateye 290. As illustrated, first exit pupil 281 is generally positioned atthe center of eye 290 and has a first size (e.g., area) that is slightly(e.g., about 10%) smaller than the pupil of eye 290. The second hologramreceives a second set of light signals 272 (represented by dotted lines)from SLP 220 and directs (e.g., redirects and/or converges) second setof light signals 272 to a second exit pupil 282 at eye 290. Asillustrated, second exit pupil 282 is generally positioned at the centerof eye 290 and has a second size (e.g., area) that is much (e.g., about100%) larger than that the pupil of eye 290. Second exit pupil 282completely encompasses first exit pupil 281 at eye 290 in theillustrated example of WHUD 200. More detail of what this means for theuser's point of view are described later on.

For the purposes of the present systems, devices, and methods, a “HOE”may or may not be transparent to certain wavelengths of light (e.g., tovisible light having a wavelength or wavelengths that is/are notprovided by SLP 220, such as most environmental light 295) while a“holographic combiner,” such as holographic combiner 230, includes a HOEthat is necessarily transparent to certain wavelengths of light (e.g.,to visible light having a wavelength or wavelengths that is/are notprovided by SLP 220, such as most environmental light 295) in order to“combine” light from SLP 220 and environmental light 295 into a singlefield of view at eye 290.

SLP 220 is shown generating (e.g., projecting) a single set of lightsignals 270 and WHUD 200 includes an optic 240 that divides, separates,or generally “splits” light signals 270 into first set of light signals271 and second set of light signals 272. In this configuration, optic240 may be an optical splitter such as those described in U.S.Non-Provisional patent application Ser. No. 15/046,254; however otherconfigurations and/or other optical structures may be employed (such as,for example, those described in U.S. Non-Provisional patent applicationSer. No. 15/046,234 and/or U.S. Non-Provisional patent application Ser.No. 15/046,269). As previously described, some implementations may notinclude an optic 240 positioned in between SLP 220 and holographiccombiner 230.

Just as various implementations may or may not include an optic 240 tosplit, replicate, or otherwise distribute light signals 270 from SLP 220en route to holographic combiner 230, the manner by which holographiccombiner 230 routes certain light signals (e.g., first set of lightsignals 271) to a first exit pupil 281 and other light signals (e.g.,second set of light signals 272) to a second exit pupil 282 may varyfrom one implementation to the next. For example, the first hologram andthe second hologram included in holographic combiner 230 may bemultiplexed holograms that implement any form of multiplexing, such asangle multiplexing, wavelength multiplexing, angle and wavelengthmultiplexing, or spatial multiplexing. In multiplexed implementations,the responsiveness of each hologram to laser light from SLP 220 isdependent on a particular property (e.g., angle of incidence,wavelength, spatial region of incidence, or any combination thereof) ofthat laser light as it impinges on holographic combiner 230.

In an angle-multiplexed example, the first hologram of holographiccombiner 230 may generally be responsive to (i.e., may direct towardsfirst exit pupil 281) first set of light signals 271 that are incidenton holographic combiner 230 over a first range of angles of incidenceand generally be unresponsive to light from SLP 220 that is incident onholographic combiner 230 at angles of incidence that are outside of thefirst range. Likewise, the second hologram of holographic combiner 230may generally be responsive to (i.e., may direct towards second exitpupil 282) second set of light signals 272 that are incident onholographic combiner 230 over a second range of angles of incidence andgenerally be unresponsive to light from SLP 220 that is incident onholographic combiner 230 at angles of incidence that are outside of thesecond range.

In a wavelength-multiplexed example, the first hologram of holographiccombiner 230 may generally be responsive to (i.e., may direct towardsfirst exit pupil 281) first set of light signals 271 that are of a firstwavelength (e.g., corresponding to laser light generated by a first oneof the R, G, or B laser diodes in laser module 221 of SLP 220) andgenerally be unresponsive to light signals of other wavelengths.Likewise, the second hologram of holographic combiner 230 may generallybe responsive to (i.e., may direct towards second exit pupil 282) secondset of light signals 272 that are of a second wavelength (e.g.,corresponding to laser light generated by a second one of the R, G, or Blaser diodes in laser module 221 of SLP 220) and generally beunresponsive to light signals of other wavelengths.

In an angle- and wavelength-multiplexed example, the first hologram ofholographic combiner 230 may generally be responsive to first set oflight signals 271 that are both: i) of a first wavelength, and ii)incident on holographic combiner 230 over a first range of angles ofincidence, and generally be unresponsive to light signals that areeither: i) of a wavelength other than the first length, and/or ii)incident on holographic combiner 230 at angles of incidence that areoutside of the first range. Likewise, the second hologram of holographiccombiner 230 may generally be responsive to second set of light signals272 that are of a different combination of wavelength and angle ofincident than first set of light signals 271 to which the first hologramis responsive. For example, the second hologram of holographic combiner230 may generally be responsive to second set of light signals 272 thatare:

a) of the first wavelength and incident on holographic combiner 230 overa second range of angles of incidence; or

b) of a second wavelength and incident on holographic combiner 230 overthe first range of angles of incidence; or

c) of a second wavelength and incident on holographic combiner 230 overa second range of angles of incidence.

In a spatially-multiplexed example, the first hologram of holographiccombiner 230 may generally be responsive to first set of light signals271 that are incident over a first holographic region of holographiccombiner 230 and generally be unresponsive to light signals that are notincident on the first holographic region of holographic combiner 230.Likewise, the second hologram of holographic combiner 230 may generallybe responsive to second set of light signals 272 that are incident overa second holographic region of holographic combiner 230 and generally beunresponsive to light signals that are not incident on the secondholographic region of holographic combiner 230.

Systems, devices, and methods for HOEs and holographic combiners thatimplement at least some of the multiplexing approaches outlined aboveare described in at least U.S. Provisional Patent Application Ser. No.62/156,736.

In the illustrated implementation of FIG. 2, holographic combiner 230comprises a single layer of holographic material (e.g., holographicfilm, photopolymer, or a silver halide compound) and both the firsthologram and the second hologram are in the single layer of holographicmaterial. However, in other implementations, holographic combiner 230may comprise multiple layers of holographic material and each respectivelayer of holographic material may include at least one respectivehologram that is operative to direct at least a respective subset oflight from SLP 220 to a respective heterogeneous exit pupil at eye 290.For example, holographic combiner 230 may comprise a first layer ofholographic material and a second layer of holographic material, wherethe second layer of holographic material is carried by the first layerof holographic material (e.g., as a laminate structure) and the firsthologram is in the first layer of holographic material and the secondhologram is in the second layer of holographic material. Generally,throughout this specification and the concept of a hologram being “in” alayer of holographic material is used to capture situations where ahologram is recorded, embedded, or otherwise stored in a layer ofholographic material but is also used in a loose sense to includesituations in which a hologram is recorded, embedded, or stored “on” alayer of holographic material (e.g., a surface relief hologram).

In WHUD 200, both the first hologram and the second hologram are in thesame layer of holographic material in holographic combiner 230 and boththe first hologram and the second hologram have substantially the samearea; however, the first hologram converges first set of light signalsto first exit pupil 281 having a first area and the second hologramconverges second set of light signals 272 to second pupil 282 having asecond, larger area. Despite both originating from substantially thesame distance and having substantially the same area, first exit pupil281 and second exit pupil 282 have different areas (e.g., differentdiameters or different shapes) because the first hologram of holographiccombiner 230 converges first set of light signals 271 to first exitpupil 281 at a first rate of convergence and the second hologram ofholographic combiner 230 converges second set of light signals 272 tosecond exit pupil 282 at a second rate of convergence. The first rate ofconvergence provided by the first hologram is greater than the secondrate of convergence provided by the second hologram, which is whatcauses, at least in part, the first area of first exit pupil 281 to beless than the second area of second exit pupil 282 at eye 290. Thisconfiguration can be advantageous for some applications, but in otherapplications it can be advantageous for multiple heterogeneous exitpupils (e.g., first exit pupil 281 and second exit pupil 282) to each berespectively formed by light having substantially the same rate ofconvergence.

Depending on the specific implementation, a WHUD that is operative toproject multiple heterogeneous exit pupils as described herein (such asWHUD 200) may optionally project all or a subset of the multipleheterogeneous exit pupils (e.g., 281, 282, and/or 283) concurrently, insequence, or “on demand” based on, for example, information from an eyetracker indicating the position of the entrance pupil to the user's eyerelative to the positions of the multiple heterogeneous exit pupils.When multiple heterogeneous exit pupils are projected concurrently,overlapping regions of adjacent exit pupils that are aligned to providethe same content to the user may result in increased brightness due tothe additive contribution of the multiple overlapping exit pupils.

FIG. 3 is an illustrative diagram showing a simplified operation of aHOE 330 that provides multiple heterogeneous exit pupils 381, 382 inaccordance with the present systems, devices, and methods. HOE 330 issimilar to holographic combiner 230 from FIG. 2 in that HOE 330converges two sets of light signals 371, 372 to two heterogeneous exitpupils 381, 382, respectively, but unlike holographic combiner 230 fromFIG. 2, HOE 330 converges both sets of light signals 371, 372 withsubstantially the same rate of convergence to respective ones ofheterogeneous exit pupils 381 and 382. HOE 330 comprises two layers ofholographic material 331, 332, where a first hologram that convergesfirst set of light signals 371 to first exit pupil 381 is in a firstlayer of holographic material 331 and a second hologram that convergessecond set of light signals 372 to second exit pupil 382 is in a secondlayer of holographic material 332. Second exit pupil 382 completelyencompasses first exit pupil 381 at eye 390 and, because both the firsthologram in first layer of holographic material 331 and the secondhologram in second layer of holographic material 332 apply substantiallythe same rate of convergence to first set of light signals 371 andsecond set of light signals 372, respectively, the optical paths ofsecond set of light signals 372 from HOE 330 to eye 390 aresubstantially parallel to the optical paths of first set of lightsignals 371 from HOE 330 to eye 390. In other words, all of the anglesof incidence of first set of light signals 371 in exit pupil 381 at eye390 are also available in in second set of light signals 372 in exitpupil 382 at eye 390.

In a virtual retina display such as scanning laser-based WHUD 200 fromFIG. 2, there may not be an “image” formed outside of the eye of theuser. There is typically no microdisplay or projection screen or otherplace where the projected image is visible to a third party; rather, theimage may be formed completely within the eye of the user. For thisreason, it may be advantageous for a scanning laser-based WHUD to bedesigned to accommodate the manner in which the eye forms an image.

For a light signal entering the eye (e.g., a light ray, a wavefront, anincident beam from a SLP, or similar), the eye (or more accurately, thecombination of the eye and the human brain) may determine “where” thelight signal is positioned in the user's field of view based on theregion of the retina that is illuminated by the light signal. Two lightsignals that illuminate the same region of the retina may appear in thesame position in the user's field of view. The particular region of theretina that is illuminated by any given light signal is determined bythe angle and not the location at which the light signal enters the eye.Thus, two light signals may appear in the same position in the user'sfield of view even if they enter different location of the user's pupilprovided that the two light signals have the same angle of incidencewhen they enter the user's eye. The geometry of the eye's lens is suchthat any two light signals entering the eye at the same angle,regardless of the position/location at which the light signals enter theeye, may generally be directed to the same region of the retina and somay generally appear in the same position in the user's field of view.

Returning to HOE 330 of FIG. 3, the fact that first exit pupil 381 andsecond exit pupil 382 both receive light signals that span the samerange of angles of incidence (due to both the first hologram and thesecond hologram of HOE 330 applying the same rate of convergence tofirst light signals 371 and second light signals 372, respectively)means that both first exit pupil 381 and second exit pupil 382 candisplay virtual content in all of the same spatial positions; however,the fact that first exit pupil 381 is smaller than the entrance pupil ofeye 390 and second exit pupil 382 is larger than the entrance pupil ofeye 390 impacts the way in which the user sees the virtual contentdisplayed thereby. First exit pupil 381 is completely encompassed by theentrance pupil of eye 390, which means that (for the pupil positionshown in FIG. 3) the user is able to see all virtual content at all ofthe spatial positions corresponding to all of the angles of incidence oflight rays that converge to first exit pupil 381 without moving theentrance pupil position of eye 390 (i.e., without changing their gazedirection). In other words, first exit pupil 381 has a relatively widefield of view for the illustrated position of the entrance pupil to eye390 but a sufficient change to the position of the entrance pupil of eye390 (i.e., a sufficient change in the gaze direction of the user) maymove the entrance pupil of eye 390 completely outside of first exitpupil 390. The result of such misalignment between first exit pupil 381and the entrance pupil of eye 390 is that the user will not be able tosee any of the display content provided by first exit pupil 381 whilefirst exit pupil 381 does not overlap at all with entrance pupil of eye390. On the other hand, second exit pupil 382 completely encompasses theentrance pupil of eye 390, which means that the user is able to seedisplay content via second exit pupil 382 over a much wider range of eyepositions and/or gaze directions (e.g., over all eye positions and/orgaze directions if second exit pupil 382 is sufficiently large) comparedto first exit pupil 381. But as a consequence of second exit pupil 382being larger than the entrance pupil of eye 390, there is no single eyeposition and/or gaze direction for eye 390 that enables the user to seeall of the display content provided by second exit pupil 382simultaneously. In other words, second exit pupil 382 provides arelatively narrow field of view and the total display area may extendoutside of this field of view. The effect may be similar to that ofgazing through a spyglass or lighting up a dark object with a spotlight:a large area of display content may be “there” but the user may need toscan their eye over a range of eye positions like a spotlight in orderto see the entire area.

The respective sizes of first exit pupil 381 (being smaller than theentrance pupil of eye 390) and second exit pupil 382 (being larger thanthe entrance pupil of eye 390) offer respective advantages anddisadvantages, at least some of which are outlined above. In accordancewith the present systems, devices, and methods, the heterogeneouscombination of a relatively small exit pupil (e.g., first exit pupil381) and a relatively large exit pupil (e.g., second exit pupil 382) cansimultaneously take advantage of the benefits of both pupil sizes whilemitigating the disadvantages of each, especially when both exit pupilsare engineered to have substantially the same convergence rates. In thecase of HOE 330, the user may see the entire display area in a largefield of view while the entrance pupil of eye 390 is positioned tocompletely encompass first exit pupil 381 as illustrated in FIG. 3 (inwhich position second exit pupil 382 is duplicative of a central“spotlight” region of the same display area, which may advantageouslyenhance brightness in the foveal region of the user's field of view),and the user may also see smaller “spotlit” views of the display areavia second exit pupil 382 when the user moves their gaze direction suchthat first exit pupil 381 no longer aligns with the entrance pupil ofeye 390. For example, if the user gazes far to the bottom of their fieldof view such that the entrance pupil of eye 390 moves completely outsideof first exit pupil 381, the user will no longer be able to see any ofthe display content via first exit pupil 381 and the user will only beable to see a “spotlight” field of view of portions from the bottom ofthe display area that converge to the bottom of second exit pupil 382;however, since the user is gazing to the bottom it is quite intuitivefor the user to only see the bottommost portions of the display area inthat eye position and such is certainly an improvement over not beingable to see any of the display area at all, as would be the case iffirst exit pupil 381 were present on its own (i.e., without the largerheterogeneous counterpart: second exit pupil 382).

In the illustrated examples of FIGS. 2 and 3, respective combinations oftwo heterogeneous exit pupils are used for illustrative purposes only.Indeed, the present systems, devices, and methods may be extended toinclude any number of exit pupils in any combination of size and/orgeometry, provided that at least two exit pupils are different from oneanother with respect to at least one of size and geometry. In otherwords, either or both of holographic combiner 230 and/or HOE 330 may beextended to include at least one additional hologram, where eachadditional hologram is engineered to receive light from the light source(e.g., the SLP 220) and direct the light to a respective exit pupil ator proximate the eye of the user. The respective exit pupilcorresponding to each additional hologram may have a respective areathat is different from the area of at least one of the other exitpupils.

FIG. 4 is an illustrative diagram of a WHUD 400 including a holographiccombiner 430 that provides multiple heterogeneous exit pupils at the eye490 of the user in accordance with the present systems, devices, andmethods. WHUD 400 includes a SLP 420 (no support structure is shown inorder to reduce clutter, similar to WHUD 200 in FIG. 2) and holographiccombiner 430 includes three spatially-multiplexed holograms each ofwhich receives light from SLP 420 over a respective holographic regionof holographic combiner 430 and redirects such light to a respectiveheterogeneous exit pupil to engineer a particular eyebox 480 at eye 490.Eyebox 480 includes: a first, relatively small area and relatively largefield of view exit pupil that is centrally positioned at eye 490(represented by the convergence of a pair of solid lines at eye 490); asecond, relatively large area and relatively small field of view exitpupil that encompasses all of the entrance pupil of eye 490 (representedby a pair of nearly parallel lines with large dashes at eye 490); and athird, relatively large area and relatively small field of view exitpupil that encompasses all of the entrance pupil of eye 490 (representedby a pair of nearly parallel dotted lines at eye 490). The configurationof eyebox 490 may allow a display interface in which the first “largefield of view” exit pupil (solid lines) may provide a “main” displayinterface at which application content is displayed but is only visibleto the user when the user is gazing straight ahead, while the second andthird “small field of view” exit pupils (dashed lines and dotted lines,respectively) may each provide a respective “narrow banner” display areaat the top and bottom, respectively, of the user's field of view that isgenerally visible to the user over a wide range of eye positions and/orgaze directions (e.g., all eye positions and/or gaze directions). Thetop and bottom “banner displays” may be used to provide, for example,notifications and other display content that the user may not wish tofocus on in much detail but that the user may wish to have presented intheir field of view regardless of the direction in which the user isgazing.

While FIG. 4 depicts an eyebox configuration in which multipleheterogeneous exit pupils are combined to provide twohorizontally-elongated rectangular (i.e., “banner”) “always visible”display regions flanking a broader central display region, the presentsystems, devices, and methods may be employed to engineer any layout ofdisplay interface depending on the specific implementation.

FIG. 5 is a flow-diagram showing a method 500 of operating a WHUD inaccordance with the present systems, devices, and methods. The WHUD maybe substantially similar to WHUD 100, WHUD 200, or WHUD 400 andgenerally includes a SLP and a holographic combiner. Method 500 includesfour acts 501, 502, 503, and 504, though those of skill in the art willappreciate that in alternative embodiments certain acts may be omittedand/or additional acts may be added. Those of skill in the art will alsoappreciate that the illustrated order of the acts is shown for exemplarypurposes only and may change in alternative embodiments. For the purposeof method 500, the term “user” refers to a person that is wearing theWHUD.

At 501, the SLP directs a first light signal towards the holographiccombiner. The first light signal may correspond to all or a portion ofan image, such as one or more pixel(s) of an image. The image mayinclude any visual representation of data, including a photograph, adrawing, text, a chart or graph, a picture, a video (e.g., a still orframe from a video or animation), and so on.

At 502, a first hologram of the holographic combiner redirects the firstlight signal towards a first exit pupil at or proximate the eye of theuser. The first exit pupil has a first area and/or a first geometry. Insome implementations, the first hologram of the holographic combiner mayredirect the first light signal by reflecting and/or converging thefirst light signal towards the first exit pupil at or proximate the eyeof the user. When the first hologram converges the first light signaltowards the first exit pupil, the first hologram may do so by applying afirst rate of convergence to the first light signal and redirecting thefirst light signal towards the eye of the user.

At 503, the SLP directs a second light towards the holographic combiner.The second light signal may correspond to all or a different portion ofthe same image as the first light signal from act 501, or the secondlight signal may correspond to all or a portion of a second image thatis different from the image to which the first light signal from act 501corresponds.

At 504, a second hologram of the holographic combiner redirects thesecond light signal towards a second exit pupil at or proximate the eyeof the user. The second exit pupil has at least one of a second areathat is different from the first area of the first exit pupil and/or asecond geometry that is different from the first geometry of the firstexit pupil. In some implementations, the second hologram of theholographic combiner may redirect the second light signal by reflectingand/or converging the second light signal towards the second exit pupilat or proximate the eye of the user. When the second hologram convergesthe second light signal towards the second exit pupil, the secondhologram may do so by applying a second rate of convergence to thesecond light signal and redirecting the second light signal towards theeye of the user, where the second rate of convergence may be differentfrom the first rate of convergence from act 502 or, as illustrated inthe example of FIG. 3, the second rate of convergence may besubstantially the same as the first rate of convergence from act 502.

As previously described, in some implementations the second hologram ofthe holographic combiner may redirect the second light signal (per act504) towards a second exit pupil that at least partially overlaps withor even encompasses the first exit pupil (from act 502) at or proximatethe eye of the user.

In some implementations, method 500 may be extended by having the SLPdirect at least one additional light signal towards the holographiccombiner. In this case, a different respective hologram of theholographic combiner may redirect each additional light signal towards adifferent respective exit pupil at or proximate the eye of the user,where each respective exit pupil may have a respective area and/orgeometry that is different from the area and/or geometry of at least oneof the other exit pupils.

The present systems, devices, and methods may be applied or otherwiseincorporated into any WHUD architecture that employs or can be adaptedto employ multiple exit pupils. For example, many WHUD architecturesthat employ waveguide structures (e.g., positioned in the field of viewof the user, such as in a transparent combiner optic) use multiple exitpupils as a means for eyebox expansion. The systems, devices, andmethods for engineering eyeboxes with heterogeneous exit pupilsdescribed herein may be applied to such architectures. At a generallevel, a WHUD that employs the present systems, devices, and methods maycomprise a support structure that in use is worn on the head of a user(e.g., support structure 110) and a display module carried by thesupport structure and operative to provide a visual display to the user(such as the combination of SLP 220 and holographic combiner 230, or aconventional combination of a microdisplay and a transparent waveguidestructure positioned in a field of view of the user and operative toroute content displayed by the microdisplay to the eye of the user). Theteachings herein may be applied to any such generic display module(e.g., to a holographic combiner or to a waveguide structure) toengineer an eyebox that reaps the benefits of heterogeneous exit pupilsby providing a first exit pupil having a first area and a second exitpupil having a second area that is different from the first area.

The term “wavelength” is used loosely herein to refer to a relativelynarrow (e.g., within 10% or 15%) waveband of light, as most “singlewavelength” laser diodes generally provide light signals over such anarrow waveband.

The HOEs described herein may generally be substantially flat or planarin geometry or, as illustrated in FIG. 2, may embody some curvature. Insome implementations, a holographic combiner (e.g., holographic combiner230) may embody curvature because the holographic combiner is carried bya prescription eyeglass lens (e.g., 250) that has some curvature. Whennecessary, an holographic combiner may include systems, devices, and/ormethods for curved holographic optical elements described in U.S.Provisional Patent Application Ser. No. 62/268,892.

A person of skill in the art will appreciate that the present systems,devices, and methods may be applied or otherwise incorporated into WHUDarchitectures that employ one or more light source(s) other than a SLP.For example, in some implementations the SLP described herein may bereplaced by another light source, such as a light source comprising oneor more light-emitting diodes (“LEDs”), one or more organic LEDs(“OLEDs”), one or more digital light processors (“DLPs”). Such non-laserimplementations may advantageously employ additional optics tocollimate, focus, and/or otherwise direct projected light signals.Unless the specific context requires otherwise, a person of skill in theart will appreciate that references to a “SLP” throughout the presentsystems, devices, and methods are generic to other light sources(combined with other optics, as necessary) that may be applied oradapted for application to accomplish the same general function(s)associated with the SLPs described herein.

A person of skill in the art will appreciate that the variousembodiments for eyeboxes comprising heterogeneous exit pupils describedherein may be applied in non-WHUD applications. For example, the presentsystems, devices, and methods may be applied in non-wearable heads-updisplays and/or in other projection displays, including virtual realitydisplays, in which the holographic combiner need not necessarily betransparent.

In some implementations that employ multiple exit pupils, all exitpupils may optionally be active at all times (allowing for temporalseparation). Alternatively, some WHUD implementations may employeye-tracking to determine the particular display region(s) towards whichthe user is gazing and may activate only the exit pupil(s) thatcorrespond(s) to where the user is looking while one or more exitpupil(s) that is/are outside of the user's field of view may bedeactivated. An eye tracker included in any of the implementations ofWHUDs described herein may employ any of a variety of different eyetracking technologies depending on the specific implementation. Forexample, an eye tracker may employ any or all of the systems, devices,and methods described in U.S. Provisional Patent Application Ser. No.62/167,767; U.S. Provisional Patent Application Ser. No. 62/271,135;U.S. Provisional Patent Application Ser. No. 62/245,792; and/or U.S.Provisional Patent Application Ser. No. 62/281,041.

Multiplexed exit pupils may advantageously enable a user to seedisplayed content while gazing in a wide range of directions.Furthermore, multiplexed exit pupils may also enable a wider variety ofusers having a wider range of eye arrangements to adequately seedisplayed content via a given WHUD. Anatomical details such asinterpupillary distance, eye shape, relative eye positions, and so oncan all vary from user to user. The various exit pupil multiplexingmethods described herein may be used, together with heterogeneous exitpupils, to render a WHUD more robust over (and therefore more usable by)a wide variety of users having anatomical differences. In order to evenfurther accommodate physical variations from user to user, the variousWHUDs described herein may include one or more mechanical structure(s)that enable the user to controllably adjust the physical position and/oralignment of one or more exit pupil(s) relative to their own eye(s).Such mechanical structures may include one or more hinge(s), dial(s),flexure(s), tongue and groove or other slidably-coupled components, andthe like. For example, at least one of the SLP and/or the opticalsplitter may be physically movable and/or rotatable on the supportstructure and the user may physically move and/or rotate the SLP and/orthe optical splitter to change a position of at least one of the N exitpupils relative to the eye. Alternatively, the approaches taught hereinmay advantageously avoid the need for inclusion of such additionalmechanical structures, allowing a smaller package and less weight thanmight otherwise be obtainable.

In some implementations, one or more optical fiber(s) may be used toguide light signals along some of the paths illustrated herein.

The various implementations described herein may, optionally, employ thesystems, devices, and methods for preventing eyebox degradationdescribed in U.S. Provisional Patent Application Ser. No. 62/288,947.

The WHUDs described herein may include one or more sensor(s) (e.g.,microphone, camera, thermometer, compass, and/or others) for collectingdata from the user's environment. For example, one or more camera(s) maybe used to provide feedback to the processor of the WHUD and influencewhere on the display(s) any given image should be displayed.

The WHUDs described herein may include one or more on-board powersources (e.g., one or more battery(ies)), a wireless transceiver forsending/receiving wireless communications, and/or a tethered connectorport for coupling to a computer and/or charging the one or more on-boardpower source(s).

The WHUDs described herein may receive and respond to commands from theuser in one or more of a variety of ways, including without limitation:voice commands through a microphone; touch commands through buttons,switches, or a touch sensitive surface; and/or gesture-based commandsthrough gesture detection systems as described in, for example, U.S.Non-Provisional patent application Ser. No. 14/155,087, U.S.Non-Provisional patent application Ser. No. 14/155,107, PCT PatentApplication PCT/US2014/057029, and/or U.S. Provisional PatentApplication Ser. No. 62/236,060.

The various implementations of WHUDs described herein may include any orall of the technologies described in U.S. Provisional Patent ApplicationSer. No. 62/242,844.

Throughout this specification and the appended claims the term“communicative” as in “communicative pathway,” “communicative coupling,”and in variants such as “communicatively coupled,” is generally used torefer to any engineered arrangement for transferring and/or exchanginginformation. Exemplary communicative pathways include, but are notlimited to, electrically conductive pathways (e.g., electricallyconductive wires, electrically conductive traces), magnetic pathways(e.g., magnetic media), and/or optical pathways (e.g., optical fiber),and exemplary communicative couplings include, but are not limited to,electrical couplings, magnetic couplings, and/or optical couplings.

Throughout this specification and the appended claims, infinitive verbforms are often used. Examples include, without limitation: “to detect,”“to provide,” “to transmit,” “to communicate,” “to process,” “to route,”and the like. Unless the specific context requires otherwise, suchinfinitive verb forms are used in an open, inclusive sense, that is as“to, at least, detect,” “to, at least, provide,” “to, at least,transmit,” and so on.

The above description of illustrated embodiments, including what isdescribed in the Abstract, is not intended to be exhaustive or to limitthe embodiments to the precise forms disclosed. Although specificembodiments of and examples are described herein for illustrativepurposes, various equivalent modifications can be made without departingfrom the spirit and scope of the disclosure, as will be recognized bythose skilled in the relevant art. The teachings provided herein of thevarious embodiments can be applied to other portable and/or wearableelectronic devices, not necessarily the exemplary wearable electronicdevices generally described above.

For instance, the foregoing detailed description has set forth variousembodiments of the devices and/or processes via the use of blockdiagrams, schematics, and examples. Insofar as such block diagrams,schematics, and examples contain one or more functions and/oroperations, it will be understood by those skilled in the art that eachfunction and/or operation within such block diagrams, flowcharts, orexamples can be implemented, individually and/or collectively, by a widerange of hardware, software, firmware, or virtually any combinationthereof. In one embodiment, the present subject matter may beimplemented via Application Specific Integrated Circuits (ASICs).However, those skilled in the art will recognize that the embodimentsdisclosed herein, in whole or in part, can be equivalently implementedin standard integrated circuits, as one or more computer programsexecuted by one or more computers (e.g., as one or more programs runningon one or more computer systems), as one or more programs executed by onone or more controllers (e.g., microcontrollers) as one or more programsexecuted by one or more processors (e.g., microprocessors, centralprocessing units, graphical processing units), as firmware, or asvirtually any combination thereof, and that designing the circuitryand/or writing the code for the software and or firmware would be wellwithin the skill of one of ordinary skill in the art in light of theteachings of this disclosure.

When logic is implemented as software and stored in memory, logic orinformation can be stored on any processor-readable medium for use by orin connection with any processor-related system or method. In thecontext of this disclosure, a memory is a processor-readable medium thatis an electronic, magnetic, optical, or other physical device or meansthat contains or stores a computer and/or processor program. Logicand/or the information can be embodied in any processor-readable mediumfor use by or in connection with an instruction execution system,apparatus, or device, such as a computer-based system,processor-containing system, or other system that can fetch theinstructions from the instruction execution system, apparatus, or deviceand execute the instructions associated with logic and/or information.

In the context of this specification, a “non-transitoryprocessor-readable medium” can be any element that can store the programassociated with logic and/or information for use by or in connectionwith the instruction execution system, apparatus, and/or device. Theprocessor-readable medium can be, for example, but is not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus or device. More specific examples (anon-exhaustive list) of the computer readable medium would include thefollowing: a portable computer diskette (magnetic, compact flash card,secure digital, or the like), a random access memory (RAM), a read-onlymemory (ROM), an erasable programmable read-only memory (EPROM, EEPROM,or Flash memory), a portable compact disc read-only memory (CDROM),digital tape, and other non-transitory media.

The various embodiments described above can be combined to providefurther embodiments. To the extent that they are not inconsistent withthe specific teachings and definitions herein, all of the U.S. patents,U.S. patent application publications, U.S. patent applications, foreignpatents, foreign patent applications and non-patent publicationsreferred to in this specification and/or listed in the Application DataSheet which are owned by Thalmic Labs Inc., including but not limitedto: U.S. Provisional Patent Application Ser. No. 62/156,736, U.S.Non-Provisional patent application Ser. No. 15/046,234, U.S.Non-Provisional patent application Ser. No. 15/046,254, U.S.Non-Provisional patent application Ser. No. 15/046,269, U.S. ProvisionalPatent Application Ser. No. 62/322,128, U.S. Provisional PatentApplication Ser. No. 62/214,600, U.S. Provisional Patent ApplicationSer. No. 62/268,892, U.S. Provisional Patent Application Ser. No.62/167,767, U.S. Provisional Patent Application Ser. No. 62/271,135,U.S. Provisional Patent Application Ser. No. 62/245,792, U.S.Provisional Patent Application Ser. No. 62/281,041, U.S. ProvisionalPatent Application Ser. No. 62/288,947, U.S. Non-Provisional patentapplication Ser. No. 14/155,087, U.S. Non-Provisional patent applicationSer. No. 14/155,107, PCT Patent Application PCT/US2014/057029, U.S.Provisional Patent Application Ser. No. 62/236,060, and/or U.S.Provisional Patent Application Ser. No. 62/242,844, are incorporatedherein by reference, in their entirety. Aspects of the embodiments canbe modified, if necessary, to employ systems, circuits and concepts ofthe various patents, applications and publications to provide yetfurther embodiments.

These and other changes can be made to the embodiments in light of theabove-detailed description. In general, in the following claims, theterms used should not be construed to limit the claims to the specificembodiments disclosed in the specification and the claims, but should beconstrued to include all possible embodiments along with the full scopeof equivalents to which such claims are entitled. Accordingly, theclaims are not limited by the disclosure.

1. A holographic optical element (“HOE”) comprising: at least one layerof holographic material, wherein the at least one layer of holographicmaterial includes: a first hologram to receive light from a light sourceand direct the light to a first exit pupil at or proximate an eye of auser, the first exit pupil having a first area; and a second hologram toreceive light from the light source and direct the light to a secondexit pupil at or proximate the eye of the user, the second exit pupilhaving a second area that is different from the first area.
 2. The HOEof claim 1 wherein the first hologram and the second hologram arepositioned and oriented with respect to one another to cause the firstexit pupil and the second exit pupil to at least partially overlap withone another at the eye of the user.
 3. The HOE of claim 2 wherein thefirst hologram and the second hologram are positioned and oriented withrespect to one another to cause the second exit pupil to encompass thefirst exit pupil at the eye of the user.
 4. The HOE of claim 1 whereinthe first hologram and the second hologram are positioned and orientedwith respect to one another to cause the first exit pupil and the secondexit pupil to be completely spatially-separated from one another at theeye of the user.
 5. The HOE of claim 1 wherein the at least one layer ofholographic material further includes at least one additional hologram,each additional hologram to receive light from the light source anddirect the light to a respective exit pupil at or proximate the eye ofthe user, and wherein each respective exit pupil has a respective areathat is different from the area of at least one of the other exitpupils.
 6. The HOE of claim 1 wherein the at least one layer ofholographic material includes a holographic material selected from agroup consisting of: a holographic film, a silver halide compound, and aphotopolymer.
 7. The HOE of claim 1 wherein the at least one layer ofholographic material includes a first layer of holographic material andboth the first hologram and the second hologram are in the first layerof holographic material.
 8. The HOE of claim 1 wherein the at least onelayer of holographic material includes a first layer of holographicmaterial and a second layer of holographic material, the second layer ofholographic material carried by the first layer of holographic material,and wherein the first hologram is in the first layer of holographicmaterial and the second holograms is in the second layer of holographicmaterial.
 9. The HOE of claim 1 wherein the first exit pupil has a firstgeometry and the second exit pupil has a second geometry that isdifferent from the first geometry.
 10. The HOE of claim 1 wherein thefirst hologram and the second hologram are both multiplexed hologramsthat implement a same form of multiplexing, the form of multiplexingimplemented by both the first hologram and the second hologram selectedfrom a group consisting of: angle multiplexing, wavelength multiplexing,angle and wavelength multiplexing, and spatial multiplexing holograms.11. The HOE of claim 1 wherein the first hologram converges the light tothe first exit pupil with a first rate of convergence and the secondhologram converges the light to the second exit pupil with the samefirst rate of convergence.
 12. A wearable heads-up display (“WHUD”)comprising: a support structure that in use is worn on a head of a user;a scanning laser projector carried by the support structure; and aholographic combiner carried by the support structure, wherein theholographic combiner is positioned within a field of view of an eye ofthe user when the support structure is worn on the head of the user, andwherein the holographic combiner comprises at least one layer ofholographic material and the at least one layer of holographic materialincludes: a first hologram to receive light from the scanning laserprojector and direct the light to a first exit pupil at or proximate theeye of the user, the first exit pupil having a first area; and a secondhologram to receive light from the scanning laser projector and directthe light to a second exit pupil at or proximate the eye of the user,the second exit pupil having a second area that is different from thefirst area.
 13. The WHUD of claim 12 wherein the support structure has ageneral shape and appearance of an eyeglasses frame, and wherein theholographic combiner further comprises an eyeglass lens that carries theat least one layer of holographic material.
 14. The WHUD of claim 12wherein the first hologram and the second hologram are positioned andoriented with respect to one another to cause the first exit pupil andthe second exit pupil to at least partially overlap with one another atthe eye of the user.
 15. The WHUD of claim 12 wherein the first hologramand the second hologram are positioned and oriented with respect to oneanother to cause the second exit pupil to encompass the first exit pupilat the eye of the user.
 16. The WHUD of claim 12 wherein the firsthologram and the second hologram are positioned and oriented withrespect to one another to cause the first exit pupil and the second exitpupil to be completely spatially-separated from one another at the eyeof the user.
 17. The WHUD of claim 12 wherein the at least one layer ofholographic material in the holographic combiner further includes atleast one additional hologram, each additional hologram to receive lightfrom the scanning laser projector and direct the light to a respectiveexit pupil at or proximate the eye of the user, and wherein eachrespective exit pupil has a respective area that is different from thearea of at least one of the other exit pupils.
 18. The WHUD of claim 12wherein the first exit pupil has a first geometry and the second exitpupil has a second geometry that is different from the first geometry.19. The WHUD of claim 12 wherein the first hologram and the secondhologram of the holographic combiner are both multiplexed holograms thatimplement a same form of multiplexing, the form of multiplexingimplemented by both the first hologram and the second hologram selectedfrom a group consisting of: angle multiplexing, wavelength multiplexing,angle and wavelength multiplexing, and spatial multiplexing.
 20. TheWHUD of claim 12 wherein the first hologram converges the light from thescanning laser projector to the first exit pupil with a first rate ofconvergence and the second hologram converges the light from thescanning laser projector to the second exit pupil with the same firstrate of convergence
 21. A method of operating a wearable heads-updisplay (“WHUD”), the WHUD including a scanning laser projector and aholographic combiner positioned within a field of view of an eye of auser when the WHUD is worn on a head of the user, the method comprising:directing a first light signal towards the holographic combiner by thescanning laser projector; redirecting the first light signal towards afirst exit pupil that has a first area at or proximate the eye of theuser by a first hologram of the holographic combiner; directing a secondlight signal towards the holographic combiner by the scanning laserprojector; and redirecting the second light signal towards a second exitpupil that has a second area at or proximate the eye of the user by asecond hologram of the holographic combiner, the second area differentfrom the first area.
 22. The method of claim 21 wherein: redirecting thefirst light signal towards a first exit pupil that has a first area ator proximate the eye of the user by a first hologram of the holographiccombiner includes converging the first light signal towards the firstexit pupil that has the first area at or proximate the eye of the userby the first hologram of the holographic combiner; and redirecting thesecond light signal towards a second exit pupil that has a second areaat or proximate the eye of the user by a second hologram of theholographic combiner includes converging the second light signal towardsthe second exit pupil that has the second area at or proximate the eyeof the user by the second hologram of the holographic combiner.
 23. Themethod of claim 21 wherein converging the first light signal towards thefirst exit pupil that has the first area at or proximate the eye of theuser by the first hologram of the holographic combiner includesconverging the first light signal towards the first exit pupil with afirst rate of convergence by the first hologram of the holographiccombiner and converging the second light signal towards the second exitpupil includes converging the second light signal towards the secondexit pupil with the same first rate of convergence by the secondhologram of the holographic combiner.
 24. The method of claim 21 whereinredirecting the second light signal towards a second exit pupil that hasa second area at or proximate the eye of the user by a second hologramof the holographic combiner includes redirecting the second light signaltowards a second exit pupil that at least partially overlaps with thefirst exit pupil at or proximate the eye of the user by the secondhologram of the holographic combiner.
 25. The method of claim 24 whereinredirecting the second light signal towards a second exit pupil that atleast partially overlaps with the first exit pupil at or proximate theeye of the user by the second hologram of the holographic combinerincludes redirecting the second light signal towards a second exit pupilthat encompasses the first exit pupil at or proximate the eye of theuser by the second hologram of the holographic combiner.
 26. The methodof claim 21, further comprising: directing at least one additional lightsignal towards the holographic combiner by the scanning laser projector;and redirecting each additional light signal towards a respective exitpupil at or proximate the eye of the user by a respective hologram ofthe holographic combiner, each respective exit pupil having a respectivearea that is different from the area of at least one of the other exitpupils.
 27. A wearable heads-up display (“WHUD”) comprising: a supportstructure that in use is worn on a head of a user; a display modulecarried by the support structure and operative to provide a visualdisplay to the user, wherein the visual display has an eyebox thatcomprises: a first exit pupil at or proximate an eye of the user, thefirst exit pupil having a first area; and at least second exit pupil ator proximate the eye of the user, the second exit pupil having a secondarea that is different from the first area.
 28. The WHUD of claim 24wherein the first exit pupil and the second exit pupil at leastpartially overlap with one another in the eyebox of the WHUD.
 29. TheWHUD of claim 24 wherein the second exit pupil encompasses the firstexit pupil in the eyebox of the WHUD.
 30. The WHUD of claim 24 whereinthe first exit pupil and the second exit pupil are completelyspatially-separated from one another and do not overlap in the eyebox ofthe WHUD.
 31. The WHUD of claim 24 wherein the eyebox of the visualdisplay further comprises at least one additional exit pupil, whereineach respective exit pupil has a respective area that is different fromthe area of at least one of the other exit pupils.